This invention relates to a method and means for providing pelvic support to improve posture and relieve lower back pain.
Most so-called secretarial or working chairs include a substantially horizontal seat member and a substantially vertical back support member. This back support member is typically positioned substantially above the seat member, and is adapted to provide support to the small of the back or lumbar region of the occupant's spinal column. The typical lumbar support chair does not, however, support the pelvis of the occupant. Thus, as will be described in detail hereafter, the occupant's pelvis is permitted to shift posteriorly and inferiorly until the coccyx or tailbone contacts the seat of the chair. In order to counteract or prevent this shifting of the pelvis, the occupant must utilize muscles which are not intended for this purpose. The use of such muscles over an extended period results in fatigue and pain. It can also result in discomfort and damage to the lumbar vertebrae and the ligaments and tendons associated with such vertebrae, as will be described in detail below.
Thus, the present invention has as its objects any one or more of the following, either taken individually or in combination with one another:
(1) To provide a method and means for supporting the pelvis in order to promote proper posture and relieve lower back pain;
(2) To provide a secretarial or working chair which will provide comfort to the occupant even after extended periods of use;
(3) To provide pelvic support without the use of extraneous means which might restrict circulation of blood and/or lymphatic fluids to the lower extremities or result in discomfort to the occupant;
(4) To provide a pelvic support chair having a seat which is high enough from the floor that the femur heads of the occupant are inclined at a slightly downward angle when the occupant's feet are resting flat on the floor, thus not only promoting circulation to the lower extremities but also relaxing the hamstring muscles of the occupant;
(5) To provide a chair in which the ischial tuberosities of the occupant are positioned proximal the uppermost portion or apex of the seat pillow;
(6) To provide a back pillow which may be used either with a conventional chair or as a supine support to produce a substantial sacral base angle in the pelvis of the user and to fully oppose any moment tending to cause rotational shifting of the pelvis.
(7) To provide a combination of a seat pillow and back pillow which can be mounted to a conventional chair to provide appropriate pelvic support; and
(8) To develop a chair which permits the occupant to achieve ligamentous posture, thereby reducing the amount of muscular and neurological exertion necessary to remain in an erect posture, and providing greater muscular control, tone, and strength for other activities undertaken while sitting in the chair; stated differently, this object is to keep the muscles of the body intact as determined by standard muscular tests.
This invention responds to the problems presented in the prior art by providing a back pillow for use in a chair having a generally horizontal seat member, wherein the back pillow includes convexly shaped support means for maintaining the pelvis of the user at a sufficient sacral base angle that substantially the entire weight of the upper portion of the body of the user is supported by the chair seat member. The term "pillow" is used herein not in the sense of a soft bed pillow, but in the sense of a common dictionary definition: "a block or support used especially to equalize or distribute pressure." The phrase "substantially the entire weight" is intended to distinguish those prior art designs which include a rearwardly tilting back adapted to support a certain portion of the weight of the occupant. Rather, it is intended to define a chair or a pillow to be used with a chair in which the pillow or chair back provides support primarily in a horizontal direction. The "upper portion of the body" is intended to define the pelvis and everything thereabove.
The invention may alternatively be described as a chair comprising a substantially horizontal, generally convex seat means for supporting the ischial tuberosities of the occupant in the vicinity of the apex thereof, in combination with substantially vertical, generally convex support means for supporting the posterior portion of the occupant's pelvis at a sacral base angle of from between 25 and 45 degrees, and so that a gravitational line drawn downwardly from the center of L-3 intersects the anterior one-third of the sacral base. Yet another way to describe the invention is the combination of seat and back pillows for use in a chair having a substantially horizontal seat member and a substantially vertical back member, wherein the seat pillow includes means for mounting the seat pillow to the seat member and has an upper surface with an apex, and wherein the back pillow includes means for mounting the back pillow to the back member and has means for supporting the pelvis of the occupant in a position such that a gravitational line drawn downwardly from the center of L-3 intersects the anterior one-third of the sacral base.